Gene Duvernoy points to big aerial photographs of the central Puget Sound region and declares that unless we act decisively in the next few years, the region's natural systems are doomed. Duvernoy is not simply urging us to repent. He argues that if we want people to do the right thing, we have to make repentance worth their while. Unfortunately, as we shall see, that last part is a very tall order.

Duvernoy is the charismatic president of the Cascade Land Conservancy, the group that made headlines in 2004 by brokering a purchase of development rights to 90,000 acres of Weyerhaeuser's old Snoqualmie tree farm. That marked a turning point in Northwestern environmentalists' attitudes toward industrial logging. Logging had always been the fate from which forests must be saved. But it was becoming clear that often, the real-world alternative to "working forest" wasn't wilderness; it was housing projects, strip malls, warehouses, golf courses, over-fertilized grass, and oily asphalt. A second-growth commercial forest will grow back in half a century or so, but as the bumper sticker says, asphalt is forever.

The Conservancy has accordingly embraced the environmental and aesthetic values of "working" landscapes. But as Duvernoy and his colleagues were congratulating themselves about their success with the tree farm, they soon realized that if they really wanted to preserve open space and natural systems over the long haul, that the tree farm purchase was just a drop in the bucket. The organization consequently put together a big, high-level, very inclusive group to work out a "Cascade Agenda" that could serve as a blueprint for preserving vast amounts of land in the central Puget Sound region.

Duvernoy's photographs show what may happen if the Cascade Agenda fails. The first one represents central Puget Sound as it is today. The urban growth boundaries established under the state Growth Management Act have been superimposed in red. Virtually all major development has taken place within the boundaries. The present looks pretty good. And if one accepts the usual "long-term" horizon of 10 to 20 years, the future looks pretty good, too.

But take a 100-year view, Duvernoy explains, and the future looks bleak. Even if you figure that only a small percentage of the region's annual growth leaks beyond the growth boundaries, but you assume — as virtually everyone does — that the local population at least doubles, and project that out over the next century, you get an awful lot of growth out in places that currently look green.

The next photo shows the same view with 100-year growth imposed on it. Pugetopolis sprawls to the Cascades. The river valleys are all paved over. The chance of salmon (or lots of other critters) surviving in a landscape like that is just about zip.

So what is to be done? Virtually no one is saying there's any way to limit population increase. Therefore, the question is where all those people will go. If you don't want them spreading out over the landscape like spilled coffee, you have to stick them into cities and towns. This means rural people can't sell their land to developers, and city people have to live in much denser neighborhoods.

Will either country people or city people go along? You can't coerce them, and you'd better not count on altruism, so you have to offer carrots. But what's in it for them? At this point, Duvernoy concedes, not much. We've understood for nearly two decades that building up urban densities was the only alternative to losing habitat and rural open space. That's what the Growth Management Act is all about. Some leaders also realized that if you want people to accept a lot more neighbors, you have to offer them something such as parks, good transit, and other improvements close to where they live.

Despite the lip service, very little of this has happened. Duvernoy says that governments should target high-density areas for infrastructure improvements and amenities, rather than spreading the goodies as evenly as possible among the voters. The city of Seattle has followed a different model, jamming increased density down people's throats, with vague promises of amenities to come later, maybe. This has touched off neighborhood backlash here as in other cities, and this is not a good example to help sell the idea to residents of other places.

Duvernoy then turns to the other side of the coin, arguing that government must make it worth rural residents' while to accept restrictions on their ability to do as they please with their land, including their right to sell it to developers. We've gone about as far as we can go with zoning and land-use regulation, Duvernoy says. Unlike a lot of environmentalists, he doesn't dismiss last year's failed property-rights initiative, I-933, as a nutcase idea that had its 15 minutes of fame. He says it reflected real, widespread discontent, and we'd better not assume that the discontent vanished when 933 went down.

King County put up some money 29 years ago, when it bought development rights to scattered agricultural land. Farmers got chunks of money that they could use as working capital — or use to stop farming. The public got the land preserved for farming — or at least open space — in perpetuity.

That agricultural bond issue cost King County voters $50 million, which represents a pittance compared to what the Cascade Agenda would cost. The Conservancy sees a price tag of $7 billion, some coming from existing funds for parks and open space. Some of the up-front money would be repaid over the long haul with income from forests and farms. Duvernoy explains that if you can get a large-enough lump of capital up front with a long-enough payoff time, you're home free.

The most problematic part of the Agenda is buying development rights to rural land that isn't self-funding because it won't produce much of an income stream. Under a program of transferable development rights, or TDR, a rural land owner sells the rights, which ultimately enable a private developer who buys these rights to exceed the underlying zoning limit some place else.

There's nothing revolutionary about transferring development rights. Seattle has been using TDRs to preserve affordable housing and historic structures since 1985. (Saving the Paramount Theater penciled out only because the City bought development rights to the property.) But it's easier said than done. It requires not only a willing buyer and a willing seller, but also a willing jurisdiction, meaning a town that accepts higher-than-zoned density in its own neighborhoods so that society can save open space somewhere else. Not many jurisdictions have been that altruistic.

Let's take three examples. In Pierce County last year a unanimous council passed a landmark ordinance, introduced by County Executive John Ladenburg, that requires anyone who wants an upzone to buy rights for additional density from rural landowners. No takers so far. The executive has subsequently introduced an ordinance that would taxes so that the county itself could get money to buy and bank the development rights. This way, a developer could just go to the county to buy rights. At present, a developer basically has to drive around and find a willing seller. But even if Pierce County acquires the funds to bank development rights, it has no authority to force new development into incorporated areas, which is where most of it should go.